Path analysis between yield components of wheat under different top-dressing nitrogen management
Alan Junior de Pelegrin¹, Maicon Nardino², Mauricio Ferrari³, Ivan Ricardo Carvalho⁴, Vinicius Jardel Szareski³, Antonio Costa de Oliveira¹, Velci Queiróz de Souza⁵ and Luciano Carlos da Maia^1
1 Universidade Federal de Pelotas, Capão do Leão, RS, Brasil
² Universidade Federal de Viçosa, Viçosa, MG, Brasil
³ SLC Agrícola, Porto Alegre, RS, Brasil
⁴ Universidade Regional do Noroeste do Estado do Rio Grande do Sul, Ijuí, RS, Brasil
⁵ Universidade Federal do Pampa, São Gabriel, RS, Brasil

Abstract
There is little research that addresses associations between the yield of wheat grains and their components in different managements of nitrogen fertilization top dressing. The objective this work linear estimate associations cause and effect between production components and the yield grains in the difference scenarios nitrogen (N) management in top dressing wheat two crops 2012 and 2013. Experimental design was randomized blocks, arranged scheme split-split-plot, with three genotypes × two crops × two source N × four management in top dressing. (3×2×2×4), in the three replications. Linear correlation and path analysis were estimate in the different N management. Management N in top dressing change magnitude linear associations in the wheat. Number fertile tillers independent management in top dressing have positive relation of cause and effect with yield grains in the wheat. Mass grains spike principal in the management II, III and IV prove positive relation cause and effect with yield grains in the wheat.

Highlighted Conclusions
1. Nitrogen management top dressing changes magnitude of linear association.
2. Number fertile tillers has positive cause relation with yield grains in wheat.
3. Mass of grains of main spike can have positive-causal relation with wheat yield grains depending on the top-dressing management.
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Univariate and multivariate controlled release nitrogen pairing on lettuce culture performance
Luiz Leonardo Ferreira¹, Alex Ribeiro Bastos¹, Ivan Ricardo Carvalho², Marilaine de Sá Fernandes¹, Núbia Sousa Carrijo dos Santos¹, Ariana Bertola Carnevale¹ and Priscila Ferreira Batista^1
1 Centro Universitário de Mineiros, Unidade de Biociências, GO, Brasil
² Universidade Regional do Noroeste do Estado do Rio Grande do Sul, RS, Brasil

Abstract
There are few studies in the literature that demonstrate the behavior of controlled release nitrogen fertilization in lettuce crop. Thus, the objective of this work was to evaluate, through univariate and multivariate pairing, the behavior of controlled release nitrogen sources on the performance of lettuce culture. The studies were conducted at the Horta dos Coqueiros property in Mineiros-GO, Brazil. The soil analyzes were taken before the experiment implementation, in the 0 to 20 cm layer, the soil was classified as NEOSSOL Quartzarenic. The experimental design was a randomized complete block design, with a 2x2x5 factorial design corresponding to 2 lettuce genotypes (Americana cv. Lucy Brow and Crespa cv. Vanda), submitted to two controlled release N sources (NitroMais and Polyblen). doses (0, 75, 150, 225, 300 kg ha^-1 of N) performing 4 repetitions. Transplantation occurred 20 days after sowing in trays, with plant spacing of 30×30. Data collection occurred 45 days after transplantation used 5 central plants of each plot. The analyzes were performed in the Rbio R interface, besides the Genes Software. The analysis of variance revealed triple interaction among the variables. Quadratic effect was expressed for both genotypes on protected nitrogen sources. For high performance of lettuce cultura in the Americana genotype cv. Lucy Brown recommends the application of protected nitrogen Polyblen at a concentration of 217.50 and NitroMais at 174.38 kg ha^-1 of N, as well as the source Polyblen at a dose of 146.50 kg ha^-1 of N in the genotype Crespa cv. Vanda.

Highlighted Conclusions
1. High performance of lettuce crop in the genotype Americana cv. Lucy Brown recommends the application of controlled release nitrogen Polyblen at a concentration of 217.50 and NitroMais at 174.38 kg ha^-1 of N.
2. In the Crespa cv. Vanda, the Polyblen source is at a dose of 146.50 kg ha^-1 of N.
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Pre-harvest herbicide application reduces the Italian ryegrass seed viability
Joanei Cechin¹, Alcimar Mazon¹, Silvio Thiago de Oliveira Raphaelli¹, Dirceu Agostinetto¹ and Leandro Vargas^2
1 Universidade Federal de Pelotas (UFPel), Pelotas-RS, Brasil
² Empresa Brasileira de Pesquisa Agropecuária (Embrapa Trigo), Passo Fundo-RS, Brasil

Abstract
Italian ryegrass (Lolium multiflorum Lam.) is a troublesome weed found in temperate agricultural fields, wherein the future infestations depend on the soil seed bank. The aim of this research was to evaluate Italian ryegrass seed viability subjected to herbicide application in different phenological stages of development. Experiments were carried out in a completely randomized experimental design with four repetitions. Paraquat, ammonium-glufosinate, iodosulfuron-methyl and clethodim herbicides were applied in three development stages (pre-spike, anthesis, and grain filling) and compared to the control. The effects were evaluated by percentage of control at seven, 14, and 28 days after application (DAA), seeds per plant, 1000 seeds weight, and percentage of germination, abnormal seedlings, dead seeds, viable and non-viable dormant seeds. Control was greater than 97% at 28 DAA, with a decrease of more 90% for seed per plant, and strong reduction of 1000 seeds weight for the herbicides applied up to the anthesis stage. At the grain filling stage, clethodim reduced seed production by 18% and 1000-seeds weight by 36% compared to the control. Ammonium-glufosinate and paraquat herbicides applied up to the anthesis stage reduced seed viability by more than 98%. Overall, herbicide application reduces seed production, seed weight and viability, especially when applied before the grain filling stage.

Highlighted Conclusions
1. Herbicide application up to the anthesis developmental stages reduces seed production, 1000 seeds weight, and seed viability.
2. Paraquat was the best herbicide to reduce seed production per plant, 1000-seeds weight and, viability of Italian ryegrass seeds, regardless of development stages.
3. Reducing future infestations of Italian ryegrass in cropping systems depends on herbicide application before the grain filling.
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Cause and effect relationships, multivariate approach for inoculation of Azospirillum brasilense in corn
Luiz Leonardo Ferreira¹, Gean Ferreira Santos¹, Ivan Ricardo Carvalho², Marilaine de Sá Fernandes¹, Ariana Bertola Carnevale¹, Karine Lopes¹, Roselaine Lages Fonseca Prado¹, Francine Lautenchleger³, Alexandre Igor de Azevedo Pereira⁴ and Carmen Rosa da Silva Curvêlo^4
1 Centro Universitário de Mineiros, Unidade de Biociências, GO, Brazil
² Universidade Regional do Noroeste do Estado do Rio Grande do Sul, Departamento de Estudos Agrários, RS, Brazil
³ Universidade do Centro-Oeste (UNICENTRO), Guarapuava, PR, Brazil
⁴ Instituto Federal Goiano, IF Goiano, Urutaí, Mineiros, GO, Brazil

Abstract
Beneficial bacteria to corn crop, such as Azospirillum brasilense, can bring consistent gains for the farmer. In this sense, the objective of this work was to evaluate the cause and effect relationships and multivariate approach of Azospirillum brasilense inoculation in corn genotypes. The study was conducted in the municipality of Mineiros-GO, Brazil. The experimental design was a randomized block in 12×2 factorial, corresponding to twelve corn hybrids (20A78, 2B587, 2B610, 30F53, CD3770, CD384, DKB310, LG36701, LG6030, MG652, P3646 and PB9110), submitted to (absence and presence) of A. brasilense. The soil preparation was carried out in the conventional system with population of 60 thousand plants. Formulated 8-25-15 at a dose of 480 kg ha^-1 was used. Pest control was performed when necessary. At the end of the experiment the variables were taken. The obtained data were submitted to the assumptions of the statistical model, verifying the normality and homogeneity of the residual variances, as well as the additivity of the model. Analyzes were performed at the Rbio interface of R and Genes. The summary analysis of variance with the mean square MS and significance by the F test revealed significant interaction between hybrid x A. brasilense. Corn hybrids showed higher expressiveness in yield components in the presence of Azospirillum brasilense applied in seed treatment. The number of grains per ear and the thousand grain mass were directly responsible for the increase of corn hybrids yield in the presence and absence of Azospirillum brasilense.

Highlighted Conclusions
1. Corn hybrids showed higher expressiveness in yield components in the presence of Azospirillum brasilense applied in seed treatment.
2. The number of grains per ear and the thousand grain mass were directly responsible for the increase of corn hybrids yield in the presence and absence of Azospirillum brasilense.
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Characterization of cassava production in the Igarapé-Açu community, Capitão Poço, Pará, Brazil
Samara Ketely Almeida de Sousa¹*, Helen Patrícia Moreira Negrão¹, Letícia do Socorro Cunha², Thiago Feliph Silva Fernandes³, Júlia Karoline Rodrigues das Mercês³, Wanderson Cunha Pereira⁴, Edmilson Barbosa do Nascimento¹, Marlon Sheldon da Silva Galdino¹ and Amanda Catarine Ribeiro da Silva^1
1 Federal Rural University of the Amazon, Capitão Poço, PA, Brazil
² State University of Western Paraná, Marechal Cândido Rondon, PR, Brazil
³ Paulista State University Júlio Mesquita de Filho, Jaboticabal, SP, Brazil
⁴ Federal University of Pará, Bragança, PA, Brazil

Abstract
The objective was to characterize the cultivation of cassava by rural producers in the Igarapé-Açu community, in the municipality of Capitão Poço, Pará, Brazil. The research involved quali-quantitative methods. For this purpose, 45 semi-structured questionnaires were applied, which included all the cassava flour producers in the Vila, in order to obtain information about the cassava and cassava flour production system, such as: size of the cultivation area, varieties used, labor used and ways of preparing the soil for cultivation. Most respondents are small farmers with an area of less than 5 ha. The cassava variety most cultivated by farmers in the village of Igarapé-Açu is mullet and about 56% of producers use exclusively family labor. As for the preparation of the soil, 40% of the interviewees perform the felling and burning. This form of tillage predominates due to the absence of technologies and causes the soil to be degraded more quickly.

Highlighted Conclusions
1. The predominant farming areas characterize family farming.
2. Producers prefer to use the mullet variety because it is easy to adapt to the region.
3. Soil preparation is still incipient in terms of the technologies used for conservationw.
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Socioeconomic profile of cassava flour producers: a study on Vila de Igarapé-Açu, Capitão Poço, Pará, Brazil
Samara Ketely Almeida de Sousa¹*, Helen Patrícia Moreira Negrão¹, Letícia do Socorro Cunha², Thiago Feliph Silva Fernandes³, Júlia Karoline Rodrigues das Mercês³, Wanderson Cunha Pereira⁴, Edmilson Barbosa do Nascimento¹, Marlon Sheldon da Silva Galdino¹ and Amanda Catarine Ribeiro da Silva^1
1 Federal Rural University of the Amazon, Capitão Poço, PA, Brazil
² State University of Western Paraná, Marechal Cândido Rondon, PR, Brazil
³ Paulista State University Júlio Mesquita de Filho, Jaboticabal, SP, Brazil
⁴ Federal University of Pará, Bragança, PA, Brazil

Abstract
The objective of this work was to characterize the socioeconomic profile of cassava flour producers, in Vila de Igarapé-Açu, Capitão Poço, Pará, Brazil. The research involved quali-quantitative methods. To this end, 45 semi-structured questionnaires were applied to all producers of manioc flour in the Vila. The questions were asked in order to obtain information about the producers’ socioeconomic profile, such as: place of birth, age, education level and sources of income. The majority of respondents, about 69%, are from the village and only 31% are from other nearby locations, mainly from the municipality of Ourém, to which the village had belonged a few years ago. Regarding the age of the interviewed producers, there was a variation between 18 and 86 years, which provides a range of 68 years. The level of education among producers is considered low, since the majority, corresponding to 73%, has not completed elementary school. About 64% earn their income entirely through the production of manioc flour. The community has the majority of Vila’s natural flour producers, with a predominant age group between 41 and 50 years old. In addition, cassava flour production is the main source of income for most of the majority of respondents.

Highlighted Conclusions
1. Most producers are from the community itself.
2. The age range of producers is 68 years old.
3. The level of education is low.
4. Flour production is the main source of income for family farmers. (more…)

Response of white oat genotypes to water stress
Danyela de Cassia da Silva Oliveira, Solange Ferreira da Silveira Silveira, Rafael Valladao Fagundes, Daiana Doring Wolter, Frederico Madabula, Victoria Freitas de Oliveira, Artur Teixeira de Araujo Jr., Clause Fatima Brum Piana, Luciano Carlos da Maia and Antonio Costa de Oliveira
Federal University of Pelotas, Pelotas, RS, Brazil

Abstract
White oat is generally cultivated in areas where there is no problem with water deficit, but due to the expansion of the cultivated areas and climate changes, there is a concern to characterize the genotypes response to water stress. The objectives of this work were to study the variability of responses of white oat cultivars, when subjected to different levels of osmotic potentials and to evaluate the genetic dissimilarity between these, with the use of REMAP markers. To study the variability, two experiments with completely randomized design, conducted in growth chambers were performed, where several oat genotypes in different osmotic potentials were evaluated. To evaluate the dissimilarity among the cultivars, REMAP markers were used. The experiments suggested the characteristics shoot (SL) and root (RL) length as the most affected by the stress. The use of the markers indicated that the similarity among the cultivars varies between 0.80 and 0.58. The study points out the cultivars URS 21, URS Corona, URS Fapa Slava as being those with the highest level of tolerance to water stress.

Highlighted Conclusions
1. The 0.8 MPa dose allows the discrimination of cultivars by performance against water stress.
2. The cultivars URS 21, URS Corona and URS Fapa Slava show better performance under water stress. (more…)

Allelopathy of weeds on the growth of vegetables
Ines Rezendes¹, Ediane Roncaglio Baseggio¹, Leandro Galon¹, Daiani Brandler¹, César Tiago Forte¹, Ignacio Aspiazú², Milena Barretta Franceschetti¹ and Alexandre Ferreira da Silva^3
1 Federal University of Fronteira Sul, Erechim, RS, Brazil.
² State University of Montes Claros, Janaúba, MG, Brazil.
³ Embrapa Milho e Sorgo, Sete Lagoas, MG, Brazil.

Abstract
The use of allelopathy emerges as an alternative method for weed management in crops, especially in small vegetable producing properties. Thus, the objective of this work was to identify possible allelopathic effects of aqueous extracts of the weeds Cyperus difformis L. (small-flowered nutsedge), Commelina benghalensis L. (benghal dayflower) and Galinsoga parviflora Cav. (gallant soldier) on seed germination and seedling growth of Lactuca sativa L. (lettuce) and Lycopersicum esculentum L. (tomato). Two experiments were carried out in a completely randomized design with five replications, the first with lettuce seeds and the second with tomato seeds submitted to germination in five concentrations of weeds aqueous extracts (0, 25, 50, 75 and 100%). All treatments with aqueous extracts of the three species, at different concentrations, caused a reduction in lettuce and tomato root length. There was a reduction in most of the evaluated variables, and seed germination of the crops had the lowest influence of the extracts. The weeds benghal dayflower, small-flowered nutsedge and gallant soldier showed allelopathic potential on lettuce and tomato crops. This potential allelopathic effect is directly related to the concentration and type of extract from the plant species. In general, it can be noted that the greatest allelopathic effect occurred with the use of small-flowered nutsedge extract, followed by gallant soldier and benghal dayflower.

Highlighted Conclusions
1. Weeds C. benghalensis, C. difformis and G. parviflora show allelopathic potential on the growth of L. sativa and L. esculentum.
2. Highest allelopathic effect is caused by the extract of C. difformis, followed by G. parviflora and C. benghalensis.
3. The potential allelopathic effect of weeds is directly related to the plant species used, as well as to the concentration of the aqueous extract present in the environment. (more…)

Associations between agronomic performance and grain chemical traits in oat
Solange Ferreira da Silveira Silveira, Danyela de Cassia Silva Oliveira, Latoia Eduarda Maltzhan, Tiago Corazza, Victoria Freitas de Oliveira, Cristiano Stulp, Henrique Pasqueti Carbonari, Vianei Rother, Maraisa Crestani Haverroth, Luis Carlos Gutkoski, Luciano Carlos da Maia and Antonio Costa de Oliveira
Federal University of Pelotas, Pelotas, RS, Brazil

Abstract
Great progress has already been achieved in breeding white oats (Avena sativa L.). However, breeders of this species need to make available to the market higher yielding and higher grain quality cultivars. Therefore, it is necessary to optimize the strategies of selection of superior genotypes. The present work aimed to estimate the correlation between traits related to agronomic performance and traits related to chemical composition of white oat grains, seeking to add understanding for the selection of higher yielding genotypes with high nutritional quality. Thirty families from the cross between the cultivars Albasul and UPF 15 were used, and 31 families from the cross between the cultivars IAC 7 and UFRGS 19. Six traits related to agronomic performance and five traits corresponding to the chemical composition of the grains were evaluated. To assess the relationship between the different traits evaluated, simple correlation and canonical correlation analyzes were performed. The results demonstrate the existence of simple correlations between grain chemical constituents and traits related to agronomic performance. The pair-by-pair relationship between traits of these two groups was also observed, but the environmental action strongly interfered with these correlations. The canonical correlation analysis allowed the verification of dependence between the evaluated trait groups where genotypes with higher number of grains per panicle, high mass of one thousand grains, with lower stature and lower number of spikelets, will have lower lipid and total fiber content, but with higher protein contents.

Highlighted Conclusions
1. There is a relationship of dependence between the agronomic performance trait group and the oat grain chemical constituent group.
2. Indirect selection of grains with higher nutritional quality and high agronomic performance will be feasible providing there is a strict control of environmental conditions.
3. Selections that seek superiority in all traits studied will not be possible, given the presence of negative correlations. (more…)

Communications in Plant Sciences, vol 9, p. 129-132, 2019 (2019021)
DOI: http://dx.doi.org/10.26814/cps2019021

Control of water hyacinth: a short review

Wilson Roberto Cerveira Junior and Leonardo Bianco de Carvalho*
*Correspondence to: leonardo.carvalho@unesp.br

Abstract: Water hyacinth (Eichhornia crassipes) is an aquatic weed native from South America that invades waterbodies of tropical and sub-tropical sites worldwide. Mechanical, chemical and biological efforts are been used to control water hyacinth. Each method of control shows advantages and disadvantages. There are no water‐use restrictions associated with mechanical control and it does not require much technical expertise, especially when plants are removed from the waterbody. However, changes in dissolved oxygen and trophic structure can accelerates eutrophication when plants are cut, leading to a subsequent increase in water hyacinth blooms. Chemical control is less labor intensive and expensive than mechanical control, especially at large scales. However, herbicides can kill non‐target algae and non‐target macrophytes, resulting in far reaching ecological impacts. Biological control is an alternative to mechanical and chemical control. It is not labor or equipment intensive, and has the potential to be self‐sustaining. However, host specificity is critical to the success of biological control and the and long-term results can discourage one to use this method. Probably, biological control is the most efficient and safety method for water hyacinth management, especially for long-term results. Mechanical and chemical control are effective for short-term results, but they can seriously impact on ecological conditions of waterbodies.

Highlighted Conclusion
1. Mechanical, chemical and biological methods are efficient to control water hyacinth.
2. Biological control is very efficient and safety for long-term control of water hyacinth.

Keywords: Eichhornia crassipes, Aquatic weed, Macrophyte, Weed control. (more…)